Previous research has shown that when a sequence of tones which alternates rapidly between two frequency categories is presented to listeners, the perceptual continuity of the pattern is lost. The tones group by frequency domain to forni two subjectively co-occurring auditory streams. The phenomenon is described as displaying a "two cnannel'* quality in that listeners nius t switch their attention rapidly betvreen streams when attempting to track tne sequence. In the present experiments listeners attempted to detect brief temporal interruptions between items of a simple auditory sequence, comprised of two high frequency tones follov/ed by tvro lower frequency tones. Temporal resolution v;as found to be most difficult when the interruption occurred between tones v^idely separated in frequency. Results are interpreted as evidence for a processing time delay when snifts of focal attention occur between "sensory cnannels" developed along the dimensions of auditory frequency.